Hot blast stove



f v March 15, 1932. A. 1 BQYNTQN 1,849,657

HOT BLAST s'rovE Filed April 17. 195o 2 sheets-sheet 1 A. J. BOYNTON HOTBLAST STOVEV March l5, 1932.

Filed April 17, 1950 2 Sheets-Shet 2 ma Z Patented Mar. l5, 1932 UNITED1s'ra'rlzs PATENT OFFICE ARTHUR J'. BOYNTON, OF WINNETKA, ILLINOIS,ASSIGNOR TO H. A. BRASSERT & COM- PANY, F CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS HOT BLAST STOVE Application led April 17,

This invention relatesv to improved means of combustion of gases withina hot blast stove preferably, though not'necessarily lim ited in itsuse, in connection with the manufacture of pig iron.

This apparatus, of which there are usually four to the furnace, consistsof a shell lined with iire brick, and a space within the lining isdivided into a combustion chamber and m checker space, both divisionsextending from the top to the bottom of the stove.

Gas is burned in the combustion chamber by admission at the bottomthrough a burner and the products of combustion rise to the i top andreverse their direction under the dome. rlhey then pass downwardlythrough the 'checkers and exit at the bottom of the stove throughsuitable chimney valves.,

By this means the interior of the stove is 2a heated.

After this heating has proceeded to a satisfactory extent, a cold blastvalve which is on the same sid-e of the stove as the chimney valves, isopened and cold air is admitted to an the bottom of the checkers andpasses upwardly to the dome, receiving in its passage a lar e incrementof temperature by contact wit i the hot brickof the checker work. Theair then passes downwardly through the cornbustion chamber and out ofthe stove through a hot blast valve, thence to the blast furnace tu res.

eretotore the individual stoves were constructed of a large size toproduce the desired heating surface in accordance with the plan ofconstruction, and a large size. is necessary to enable the volume o airrequired by the blast furnace to be heated to a temperature up to 1500oor 1600o F. maximum.

The number of stoves provided per furnace has been determined by the-conditions of operation where unwashed blast furnace gas is used forheating thel stoves, as well as by limitation of the amount of gas whichcan be burned within a given length of time.

The result of these two causes has been a usual provision loi fourstoves per furnace, thereby permitting the use of three when one stoveis ofor cleaning.

Under the circumstances of operation, it

1930. serial No. 444,918.

is consequently permissible to take from two to three times the lengthof the air period for heating the stove, and the rate of admission ofgas for combustionwithin the stove is corlrespondingly slow.

With the advent of washed gas, the number of stoves may be reduced tothree with emergency use of two, one on gas and one on air, and asidefrom consideration of delay in operation it is now possibleto operatecontinuously with two stoves, excepting for the fact that diculty hasbeen heretofore encountered in burning the large amount of gas requiredto be burned where the length of the heating and cooling phases of stoveoperation are equalized. v y

it is one of the objects of the present invention to provide. improvedmeans for increasing the amount of gas which may be burned per stove perunit of time.

A definite limitation with regard to the amount of gas which can beburned in a unit of time in a combustion chamber of a given size hasbeen heretofore found in the inability of the means employed to secure asteady and continuous combustion of the gas.

With the high rate of iniux of gas and air to the combustion chamber andwith ignition from the hot walls, combustion takes place in a series ofshort explosions which result in what is known as puiiing which isalways troublesome and which in some cases results in damage to thestructureof the stove lining.

The intensity of this pufing is increased by the admitting oi largerquantities of gas and air to the stove.

It is another object of the present invention to overcome thesediiiculties andobjections and to provide improved means Jfor eectingregular and even combustion of large quantities of gas. This isaccomplished by providing a combustion chamber in which has beenconstructed a refractory screen.' This screen is in conical form and issituated in the lower portion of the combustion chamber, preferably asshown in Figure 1 of the drawings. The application of the screen in themanner shown has the function of preventing combustion of the gases inthe inlet flue 20 and the lower portion of the chamber 1l adjacentthereto. Combustion of the gases is prevented due to the high velocityof the air and gas mixture while passing through the screen openings.Due to its high velocity combustion is prevented in the flue 2O and inthe chamber adjacent thereto. After the gases pass through the screenopenings combustion is promoted, due to the combination of two effects.First,'on account of the lower gas velocity in the combustion chamberabove the screen, and second, to the heat obtained from the hot walls ofthe combustion chamber, combustion takes place at the outer wall of theconical screen. The screen is constructed in a conical shape for twopurposes, first, simplicity of construction, and second because anydesired area for How of gases may be obtained by increasing ordecreasing the size of the openings and the size of the conicalsections.

To the attainment of these ends and the accomplishment of other new anduseful objects as will appear, the invention consists in the features ofnoveltyin substantially the construction, combination and arrangement ofthe several parts hereinafter more fully described and claimed and shownin the accompanying drawings illustrating this invention and in whichFigure 1 is a vertical, longitudinal, sectional View of a stove of thischaracter constructed in accordance with the principles of thisinvention.

Figure 2 is a horizontal sectional View taken on line 2 2, Figure 1.

Figure 3 is an enlarged detail transverse sectional View of a portion ofthe checkers.

Figure 4 is a detail perspective view of one of the checker elements.

Referring more particularly to the drawings the numeral 10 designatesgenerally the shell of the stove having a dome 11, the shell and domebeing lined with suitable fire brick lining 12.

Within the shell is arranged a partition 13 which extends from thebottom 14 of the stove towards and terminates short of the dome todivide the stove into a combustion space 15 and a checker space 16 andwhich spaces are connected by means of a passage 17 adjacent the dome12.

Arranged within the combustion space, preferably adjacent or inproximity to the bottom thereof is a conically shaped refractory screen18 provided with openings 19 therethrough and this screen is of anydesired configuration in cross section and is hollow so that the gas andair ,which is admitted into the stove from a mixing burner through apassageway 20 will be delivered beneath the conical screen and will flowthrough the apertures 19 to be ignited at the outer surface of thescreen.

Arranged at any suitable pointabove the base of the screen 19 is anopening 21 closed aeaaem by a suitable closure 22 and this opening isrovided for the purpose of preliminary lgnition of the combustivemixture at the outside of the screen 18.

Arranged within the checker space 16 are suitable checkers 23 which arehollow as at 24 and open at both ends. The checkers are preferablyrectangular in cross section and the outer corners thereof are cut awayto form beveled surfaces 25 so that when a plurality of the checkers areassembled as shown in Figure 3, there will be provided circulatingspaces through and between the checkers thereby increasing to a maximumthe radiating surfaces within the checker space.

The products of combustion in the chamber 15 will rise therein to thetop of the stove and will pass through the passage 17 beneath the domell, reversing their direction of flow underv the dome and will then passdownwardly through the checkers 23 and exit at the bottom of the stovethrough suitable passages 26 controlled by suitable chimney valves (notshown).

During the passage of the products of comn bustion through the checkersthe interior of the stove will be heated to any desired temperature.

After the heating has proceeded to a satisfactory extent the supply offuel through the opening 20 is cut off and a blast of cold air will beadmitted through an opening 27 which is located on the same side of thestove as the chimney Valves and the outlet passage 26, to the bottom ofthe checkers 23 in the checker space 16.

This cold air will pass upwardly through the checkers 23 to the dome l1flowing through the passage 17 into the combustion -chamber 15 and will,during such passage receive or absorb a large increment of thetemperature by contact with the brick and the checker surfaces.

The air then flows downwardly through the combustion chamber 15 and outof the chamber through a. assage 28 through hot blast valves 29 and romthence to the blast furnace tuyres.

By reason of the small apertures in the conical member the mixture ofair and gas will be ignited on the outer surface of the cone andpropagation of the flame backward through the cone is prevented by thevelocity of the air and gas entering the opening and by the relativelylow temperature on the under side of the cone which is maintained by theconstant passage of cold air and gas.

While the preferred form of the invention has been herein shown anddescribed, it is to be understood that various changes may be made inthe details of construction and in the combination and arrangement ofthe several parts, within the scope of the claims, without departingfrom the spirit of this invention.

What is claimed as new is 1. In a hot blast stove, a combustion chamber,an apertured refractory screen in said chamber and through which screenthe gas and airforits combustion pass, said screen being of a conicalformation to provide a maximum outer surface, said surface co-op cratingwith the hot walls of the combustion chamber whereby an intensetemperature will be created at the outer surface of said screen andcombustion will be promoted, means whereby a mixture of air and gas maybe discharged into the combustion chamber below the said screen, and anair door opening into the combustion chamber above th said screen.

2. In a hot blast stove, a combustion cham y ber, a`conical refractoryscreen in said chamber, said screen having comparatively small openingstherethrough, and means whereby 'a mixture of gas and air may beadmitted through said screen, combustion in said chamber being initiatedat the outer surface of said screen.

screen in said combustion chamber across the pathof flow of the air andgas mixture'in the combustion chamber, and means whereby a mixture ofgas and air may be introduced into the combustion chamber at a pointbelow said screen.

-lln testimony whereof I have signed m name to this specification onthis th day of April, A. D. 1930.

- ARTHUR J. BOYNTON.

'3. ln a hot blast stove, a combustion chamB Y ber, an aperturedrefractory screen against one surface of which combustion is initiated,said surface being of an area considerably greater than the'transversearea of the portion of the combustion chamber in which said.

surface is located, and a gas supply inlet be-l I l low said screen.

4. In a hot blast stove, a combustion chamber, an apertured conicalrefractory screen located in the lowerportion of said chamber n. andagainst one surface of which combustion is initiated, said surface beingof an area considerably greater than the transverse area of the portionof the combustion chamber in which said surface is-located, and an airdoor opening into said combustion chamber above said screen.

5. `'A hot blast stove embodying a shell lined with refractory material,a partition 'introduced into said combustion chamber beneath saidscreen.

6. Av hot blast stove embodying a shell lined with refractory material,a partition A dividing said shell into a combustion chamber and achecker space, there being a communicating passage between said chamberand said checker space adjacent the top of said shell, an aperturedconical refractory

